/* ===== Reset & base ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #ffffff;
  --bg-alt: #f6f8fb;
  --surface: #ffffff;
  --surface-2: #f0f3f8;
  --border: #e3e8f0;
  --text: #10182b;
  --text-muted: #5f6b81;
  --teal: #2bb8c4;
  --blue: #1554d8;
  --gradient: linear-gradient(135deg, var(--teal), var(--blue));
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --shadow: 0 20px 45px rgba(16, 24, 40, 0.1);
  --shadow-sm: 0 2px 10px rgba(16, 24, 40, 0.06);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

img, svg {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

button {
  font: inherit;
  cursor: pointer;
}

section {
  scroll-margin-top: 84px;
}

.container {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
}

.eyebrow {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: 12px;
}

.section-head {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 56px;
}

.section-head h2 {
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  margin-bottom: 14px;
}

.section-head p {
  color: var(--text-muted);
  font-size: 1.05rem;
}

.gradient-text {
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  white-space: nowrap;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--gradient);
  color: #ffffff;
  box-shadow: 0 10px 30px rgba(22, 80, 214, 0.25);
}

.btn-primary:hover {
  box-shadow: 0 14px 36px rgba(22, 80, 214, 0.35);
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-ghost:hover {
  border-color: var(--teal);
  color: var(--teal);
}

.btn-block {
  width: 100%;
}

.btn:disabled,
.btn[disabled] {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
}

/* ===== Header ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.78);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(16, 24, 40, 0.06);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.15rem;
}

.brand .logo-mark {
  width: 26px;
  height: 40px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--text-muted);
  transition: color 0.15s ease;
}

.nav-links a:hover {
  color: var(--text);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 18px;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  padding: 8px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  padding: 168px 0 120px;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(43, 184, 196, 0.16), transparent 70%);
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  bottom: -260px;
  left: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(21, 84, 216, 0.14), transparent 70%);
  pointer-events: none;
}

.hero-grid {
  position: relative;
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero-copy h1 {
  font-size: clamp(2.2rem, 4.4vw, 3.4rem);
  line-height: 1.15;
  margin-bottom: 22px;
}

.hero-copy p {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 520px;
  margin-bottom: 34px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  font-size: 0.82rem;
  color: var(--text-muted);
}

.badge svg {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
}

/* ---- Hero device mockup (FChat app UI) ---- */
.hero-visual {
  position: relative;
  display: flex;
  justify-content: center;
}

.device-frame {
  width: 100%;
  max-width: 300px;
  background: #14161e;
  border-radius: 44px;
  padding: 12px;
  box-shadow: var(--shadow);
}

.device-screen {
  background: var(--surface);
  border-radius: 32px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  min-height: 560px;
}

.app-topbar {
  background: var(--gradient);
  padding-bottom: 22px;
}

.status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 22px 6px;
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text);
}

.status-icons {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--text);
}

.status-icons svg:first-child {
  width: 16px;
  height: 10px;
}

.status-icons svg:last-child {
  width: 20px;
  height: 11px;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px 0;
  color: #ffffff;
}

.app-title {
  font-weight: 800;
  font-style: italic;
  font-size: 1.3rem;
  letter-spacing: -0.02em;
}

.app-header-icons {
  display: flex;
  align-items: center;
  gap: 16px;
}

.app-header-icons svg {
  width: 19px;
  height: 19px;
  flex-shrink: 0;
}

.app-search {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: -16px 16px 6px;
  padding: 11px 16px;
  background: var(--surface);
  border-radius: 999px;
  color: var(--text-muted);
  font-size: 0.85rem;
  box-shadow: var(--shadow-sm);
  position: relative;
  z-index: 1;
}

.app-search svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

.chat-list-label {
  padding: 6px 18px 4px;
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.chat-list {
  display: flex;
  flex-direction: column;
  flex: 1;
}

.chat-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 18px;
  border-bottom: 1px solid var(--border);
}

.chat-row:last-child {
  border-bottom: none;
}

.chat-avatar-sm {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  font-weight: 700;
  font-size: 0.82rem;
  flex-shrink: 0;
}

.avatar-1 { background: #5b6bd6; }
.avatar-2 { background: var(--gradient); }
.avatar-3 { background: #2f8fe0; }
.avatar-4 { background: #38b6c2; }
.avatar-5 { background: #8b93a7; }

.chat-row-main {
  flex: 1;
  min-width: 0;
}

.chat-row-top,
.chat-row-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.chat-row-top {
  margin-bottom: 3px;
}

.chat-name {
  flex: 1;
  min-width: 0;
  font-weight: 600;
  font-size: 0.88rem;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.chat-time {
  font-size: 0.7rem;
  color: var(--text-muted);
  flex-shrink: 0;
}

.chat-preview {
  font-size: 0.8rem;
  color: var(--text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.chat-preview.typing {
  color: var(--teal);
  font-style: italic;
}

.app-tabbar {
  display: flex;
  justify-content: space-around;
  align-items: center;
  padding: 10px 0 16px;
  border-top: 1px solid var(--border);
  margin-top: auto;
}

.tab-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  color: var(--text-muted);
}

.tab-item svg {
  width: 21px;
  height: 21px;
}

.tab-label {
  font-size: 0.6rem;
  font-weight: 600;
}

.tab-item.active {
  color: var(--teal);
}

/* ===== Trust strip ===== */
.trust-strip {
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: var(--bg-alt);
  padding: 22px 0;
}

.trust-strip .container {
  display: flex;
  flex-wrap: wrap;
  gap: 28px;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.trust-strip .item {
  display: flex;
  align-items: center;
  gap: 8px;
}

.trust-strip svg {
  width: 16px;
  height: 16px;
  color: var(--teal);
}

/* ===== Features ===== */
.features {
  padding: 120px 0;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: 30px;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--teal);
  box-shadow: var(--shadow);
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  background: var(--gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.feature-icon svg {
  width: 24px;
  height: 24px;
  color: #fff;
}

.feature-card h3 {
  font-size: 1.1rem;
  margin-bottom: 10px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.94rem;
}

/* ===== Platforms / Download ===== */
.platforms {
  padding: 120px 0;
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.platform-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.platform-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: 28px 22px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.soon-tag {
  position: absolute;
  top: 14px;
  right: 14px;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.platform-icon {
  width: 52px;
  height: 52px;
  margin-bottom: 18px;
  color: var(--teal);
}

.platform-icon svg {
  width: 100%;
  height: 100%;
}

.platform-card h3 {
  font-size: 1.05rem;
  margin-bottom: 6px;
}

.platform-card .req {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.platform-note {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.88rem;
  margin-top: 40px;
}

/* ===== Support / FAQ ===== */
.support {
  padding: 120px 0;
}

.faq-list {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.faq-item summary {
  list-style: none;
  cursor: pointer;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  font-weight: 600;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item .chevron {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: var(--teal);
  transition: transform 0.2s ease;
}

.faq-item[open] .chevron {
  transform: rotate(180deg);
}

.faq-item .faq-answer {
  padding: 0 24px 20px;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.support-cta {
  text-align: center;
  margin-top: 44px;
  color: var(--text-muted);
}

.support-cta a {
  color: var(--teal);
  font-weight: 600;
}

/* ===== Contact ===== */
.contact {
  padding: 120px 0;
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
}

.contact-wrap {
  max-width: 640px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 44px;
}

.form-row {
  margin-bottom: 20px;
}

.form-row label {
  display: block;
  font-size: 0.88rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-muted);
}

.form-row input,
.form-row textarea {
  width: 100%;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 13px 16px;
  color: var(--text);
  font: inherit;
  font-size: 0.95rem;
  transition: border-color 0.15s ease;
}

.form-row input:focus,
.form-row textarea:focus {
  outline: none;
  border-color: var(--teal);
}

.form-row textarea {
  resize: vertical;
  min-height: 120px;
}

.form-status {
  display: none;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  background: rgba(43, 184, 196, 0.1);
  border: 1px solid rgba(43, 184, 196, 0.3);
  color: var(--text);
  font-size: 0.92rem;
}

.form-status.visible {
  display: flex;
}

.form-status svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: #0d7d86;
}

.contact-alt {
  text-align: center;
  margin-top: 28px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.contact-alt a {
  color: var(--teal);
  font-weight: 600;
}

/* ===== Footer ===== */
.site-footer {
  padding: 60px 0 30px;
  border-top: 1px solid var(--border);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.footer-brand {
  max-width: 320px;
}

.footer-brand .brand {
  margin-bottom: 14px;
}

.footer-brand p {
  color: var(--text-muted);
  font-size: 0.92rem;
}

.footer-links {
  display: flex;
  gap: 60px;
  flex-wrap: wrap;
}

.footer-col h4 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-col a {
  font-size: 0.92rem;
  color: var(--text);
}

.footer-col a:hover {
  color: var(--teal);
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }

  .hero-visual {
    order: -1;
  }

  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .platform-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 720px) {
  .nav-links,
  .nav-actions .btn-ghost {
    display: none;
  }

  .nav-toggle {
    display: flex;
  }

  .site-header.open .nav-links {
    display: flex;
    position: absolute;
    top: 76px;
    left: 0;
    right: 0;
    background: var(--bg);
    flex-direction: column;
    align-items: flex-start;
    padding: 20px 24px 30px;
    gap: 20px;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
  }

  .hero {
    padding: 130px 0 80px;
  }

  .feature-grid {
    grid-template-columns: 1fr;
  }

  .platform-grid {
    grid-template-columns: 1fr;
  }

  .contact-wrap {
    padding: 30px 22px;
  }

  .footer-top {
    flex-direction: column;
  }
}